Optical disc apparatus and recording power determining method thereof

ABSTRACT

A method of determining a recording power used to record information to an optical disc, includes carrying out test recording which records predetermined data to a predetermined area of the optical disc to determine the recording power, and recording predetermined data with a power equal to or more than the determined recording power to an area adjacent to the predetermined area.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of determining optimumrecording power in optical disc apparatus for recording information byirradiating optical discs with a laser beam.

2. Related Art

Optical discs have been extensively developed as a means for recording alarge volume of data, and for one of them, there is a write-once typeoptical disc which utilizes the state change of organic pigment and canrecord information once only in one same place. In the optical disc thatuses organic-based pigment for recording film, the vapor pressure in thevicinity of the surface of the recording portion is raised byirradiation of an optimum light beam and presses to expand the meltedportion to the periphery to form a pit.

In recording information to such a kind of optical disc, it is importantto optimize the irradiation power of light beam, and accordingly amethod of carrying out test recording in the predetermined area of theoptical disc has been extensively adopted. In such event, since the areaonce recorded cannot be reused in the write-once type optical disc, itis necessary to search for the unused area for carrying out the testrecording. For example, the unused area can be found by detecting thereflecting light quantity by scanning the test recording area with lightbeam, using the difference of reflectance between the used area and theunused area.

However, because by the conventional technique, in the area where eventhough recording was carried out, the recording was not satisfactory dueto, for example, stains of light pickup, etc., there was a problem inwhich changes of reflecting light quantity were small. Thus the usedarea was mistakenly judged to be an unused area during searching thetest recording area and the test recording was carried out thereto.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a recording methodcapable of surely detecting the unused area for test recording when thetest recording is carried out in a write-once type optical discs.

In the first aspect of the invention, provided is a method ofdetermining a recording power used to record information to an opticaldisc. The method includes determining the recording power by carryingout test recording which records predetermined data to a predeterminedarea of the optical disc, and recording predetermined data with a powerequal to or more than the determined recording power to an area adjacentto the predetermined area.

On the optical disc, a light spot may move in the direction from theinner periphery to the outer periphery of the optical disc, and thepredetermined area may be used from the outer part to carry out the testrecording. In this case, the adjacent area may be on the inside of anarea where the test recording has been carried out in the predeterminedarea.

Alternatively, on the optical disc, a light spot may move in thedirection from the inner periphery to the outer periphery of the opticaldisc, and the predetermined area may be used from the inner part tocarry out the test recording. In this case the adjacent area may be onthe outside of an area where the test recording has been carried out inthe predetermined area.

Alternatively, on the optical disc, a light spot may move in thedirection from the outer periphery to the inner periphery of the opticaldisc, and the predetermined area may be used from the outer part tocarry out the test recording. In this case, the adjacent area may be onthe inside of an area where the test recording has been carried out inthe predetermined area.

Alternatively, on the optical disc, a light spot may move in thedirection from the outer periphery to the inner periphery of the opticaldisc, and the predetermined area may be used from the inner part tocarry out the test recording. In this case the adjacent area may be onthe outside of an area where the test recording has been carried out inthe predetermined area.

In the recording power determining method, the predetermined data may berecorded with the determined recording power to areas inside and outsideof a part area of the predetermined area in which test recording hasbeen just carried out.

In the second aspect of the invention, provided is a method ofdetermining a recording power used to record information to an opticaldisc. The method includes carrying out test recording which records apredetermined data to a predetermined test recording area to determinethe recording power while a light spot moves in the direction from theinner periphery to the outer periphery and the predetermined testrecording area is used from the outer part, and updating the recordingpower used for the test recording for each predetermined area from thehigh power to the low power.

In the third aspect of the invention, provided is a method ofdetermining a recording power used to record information to an opticaldisc. The method includes carrying out test recording which records apredetermined data to a predetermined test recording area to determinethe recording power while a light spot moves in the direction from theinner periphery to the outer periphery and the predetermined testrecording area is used from the inner part, and updating the recordingpower used for the test recording for each predetermined area from thelow power to the high power.

In the fourth aspect of the invention, provided is a method ofdetermining a recording power used to record information to an opticaldisc. The method includes carrying out test recording which records apredetermined data to a predetermined test recording area to determinethe recording power while a light spot moves in the direction from theouter periphery to the inner periphery and the predetermined testrecording area is used from the outer part, and updating the recordingpower used for the test recording for each predetermined area from thelow power to the high power.

In the fifth aspect of the invention, provided is a method ofdetermining a recording power used to record information to an opticaldisc. The method includes carrying out test recording which records apredetermined data to a predetermined test recording area to determinethe recording power while a light spot moves in the direction from theouter periphery to the inner periphery and the predetermined testrecording area is used from the inner part, and updating the recordingpower used for the test recording for each predetermined area from thehigh power to the low power.

In the sixth aspect of the invention, provided is a method ofdetermining a recording power used to record information to an opticaldisc. The method includes carrying out test recording which recordspredetermined data to a predetermined area of the optical disc todetermine the recording power, and when the recording is interruptedduring the test recording to the predetermined area, resuming recordingwith a predetermined power the data to the predetermined area in whichthe recording is interrupted.

In the above recording power determining methods, the optical disc maybe of the write-once type.

In the seventh aspect of the invention, provided is an apparatus forrecording information to an optical disc. The apparatus includes a powerdetermining section that determines a recording power by carrying outtest recording which records predetermined data to a predetermined areaof the optical disc, and a recording section that records predetermineddata with a power equal to or more than the determined recording powerto an area adjacent to the predetermined area.

In the eighth aspect of the invention, provided is an apparatus forrecording information to an optical disc. The apparatus includes a testrecording section that carries out test recording to record apredetermined data to a predetermined test recording area fordetermining the recording power while a light spot moves in thedirection from the inner periphery to the outer periphery and thepredetermined test recording area is used from the outer part, and anupdate section that updates the recording power used for the testrecording for each predetermined area from the high power to the lowpower.

In the ninth aspect of the invention, provided is an apparatus forrecording information to an optical disc. The apparatus includes a testrecording section that carries out test recording to record apredetermined data to a predetermined test recording area fordetermining the recording power while a light spot moves in thedirection from the inner periphery to the outer periphery and thepredetermined test recording area is used from the inner part, and anupdate section that updates the recording power used for the testrecording for each predetermined area from the low power to the highpower.

In the tenth aspect of the invention, provided is an apparatus forrecording information to an optical disc. The apparatus includes a testrecording section that carries out test recording to record apredetermined data to a predetermined test recording area fordetermining the recording power while a light spot moves in thedirection from the outer periphery to the inner periphery and thepredetermined test recording area is used from the outer part, and anupdate section that updates the recording power used for the testrecording for each predetermined area from the low power to the highpower.

In the eleventh aspect of the invention, provided is an apparatus forrecording information to an optical disc. The apparatus includes a testrecording section that carries out test recording to record apredetermined data to a predetermined test recording area fordetermining the recording power while a light spot moves in thedirection from the outer periphery to the inner periphery and thepredetermined test recording area is used from the inner part, and anupdate section that updates the recording power used for the testrecording for each predetermined area from the high power to the lowpower.

In the twelfth aspect of the invention, provided is an apparatus forrecording information to an optical disc. The apparatus includes a testrecording section that carries out test recording which recordspredetermined data to a predetermined area of the optical disc todetermine the recording power, and a resume section that, when therecording is interrupted during the test recording in the predeterminedarea, resumes recording with a predetermined power the data to thepredetermined area in which the recording is interrupted.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other object and features of the present invention will becomeclear from the following description taken in conjunction with thepreferred embodiments thereof with reference to the accompanyingdrawings, in which:

FIG. 1 is a block diagram of an optical disc apparatus according to thepresent invention;

FIG. 2 is a diagram showing areas logically provided on the opticaldisc;

FIG. 3 is a diagram showing the test recording area and the recordingstatus of each sector in the area;

FIG. 4A shows each sector of test recording area; FIG. 4B shows theoutput signal of the recording section; FIG. 4C shows the recordingpower for test recording in each sector; FIG. 4D shows a kind of marksrecorded in each sector; FIG. 4E shows the output signal of thereproducing section; FIG. 4F shows asymmetry values; FIG. 4G shows 3Tcontinuous signals; FIG. 4H shows 3T continuous signals with pulse widthmodulated; FIG. 4I shows 11T continuous signals; FIG. 4J shows 11Tcontinuous signal with pulse width modulated;

FIG. 5 is a block diagram of the laser drive circuit;

FIG. 6 is a diagram explaining the asymmetry detection method;

FIGS. 7A through 7C show sectors, recording power, and asymmetry valuesafter the first test recording is carried out, respectively; FIGS. 7Dthrough 7F show sectors, recording power, and asymmetry values after thesecond test recording is carried out, respectively;

FIG. 8 is a diagram showing the recording status of sectors of the testrecording area in the condition when the second test recording isfinished;

FIG. 9 is a diagram showing the recording condition of the testrecording area;

FIG. 10 is a table showing various modes in the light spot movingdirection and the direction of using test recording area in an opticaldisc;

FIG. 11 is a diagram schematically showing the test recording areas onan optical disc;

FIG. 12 is a diagram explaining the modulation degree detected at thereproducing signal quality inspection section;

FIG. 13 is a diagram explaining one mode in the light spot movingdirection and the use direction of test recording area in an opticaldisc;

FIG. 14 is a diagram explaining another mode in the light spot movingdirection and the direction of using test recording area in an opticaldisc;

FIG. 15 is a diagram explaining the other mode in the light spot movingdirection and the use direction of test recording area in an opticaldisc;

FIG. 16 is a diagram explaining the other mode in the light spot movingdirection and the use direction of test recording area in an opticaldisc;

FIG. 17 is a diagram showing the configuration of a multilayer opticaldisc;

FIG. 18 is a table showing various modes in the light spot movingdirection and the use direction of test recording area in a multilayeroptical disc;

FIGS. 19A and 19B are diagrams explaining one mode in the light spotmoving direction and the direction of using test recording area on firstand second recording layers of a multilayer optical disc, respectively;

FIGS. 20A and 20B are diagrams explaining other mode in the light spotmoving direction and the direction of using test recording area on firstand second recording layers of a multilayer optical disc, respectively;

FIGS. 21A and 21B are diagrams explaining other mode in the light spotmoving direction and the direction of using test recording area on firstand second recording layers of a multilayer optical disc, respectively;

FIGS. 22A and 22B are diagrams explaining other mode in the light spotmoving direction and the direction of using test recording area on firstand second recording layers of a multilayer optical disc, respectively;

FIGS. 23A and 23B are diagrams explaining other mode in the light spotmoving direction and the direction of using test recording area on firstand second recording layers of a multilayer optical disc, respectively;

FIGS. 24A and 24B are diagrams explaining other mode in the light spotmoving direction and, the direction of using test recording area onfirst and second recording layers of a multilayer optical disc,respectively;

FIGS. 25A and 25B are diagrams explaining other mode in the light spotmoving direction and the direction of using test recording area on firstand second recording layers of a multilayer optical disc, respectively;

FIGS. 26A and 26B are diagrams explaining other mode in the light spotmoving direction and the direction of using test recording area on firstand second recording layers of a multilayer optical disc, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the accompanied drawings, preferred embodiments of theoptical disc apparatus according to the present invention will bedescribed in detail hereinafter.

<1. Configuration of the Optical Disc Apparatus>

FIG. 1 shows the configuration of the optical disc apparatus in oneembodiment according to the present invention. In FIG. 1, the opticaldisc apparatus is an apparatus for recording information to an opticaldisc 101, and includes an optical head 102, reproducing section 103,reproducing signal quality detection section 104, optimum recordingpower determining section 105, recording section 106, laser drivecircuit 107, recording power setting section 108 and test recording areasearching section 109. The optical disc 101 referred to here is awrite-once optical disc which can record information only once to thesame place.

<2. Data Structure of Optical Disc>

FIG. 2 is a diagram showing areas logically formed on the optical disc101 in the present embodiment. As shown in FIG. 2, the optical disc 101includes a control area 201 with disc type, etc. recorded, a testrecording area 202 for determining a recording power (optimum recordingpower) most suited for recording the data, and a data area 203. Now, atleast the test recording area 202 and the data area 203 are configuredso as to have groove-form tracks which are connected in a spiral formand on which the information is recorded. It is noted that the track isformed by units called block, sector and frame, in which one sector isformed with a plurality of frames and one block is formed with aplurality of sectors.

The block is a recording unit to which error correction is applied, andat least in the data area 203, recording operation is performed in unitsof blocks. According to the present embodiment, in the test recordingarea 202, test recording is carried out with a plurality of recordingpowers, updating the recording power at each sector. However, the timingof updating the recording power is not limited to this, it may be ateach block or each frame.

In the control area 201, the initial information may be recorded withconcavo-convex pits. Alternatively, it may be recorded with the opticalmeans same as that for recording the information in the data area 203before shipment from the plant, when the control area is formed with agroove-form track as in the case of the data area 203.

Though in the present embodiment the test recording area 202 is locatedinside the control area 201, the location of the test recording area 202is not limited to this, but for example, may be arranged adjacent to thedata area 203.

Considering the warpage of the disc, the shorter the distance betweenthe test recording area 202 and the data area 203, the closer is thedegree of warpage, and it is possible to find the recording power moreaccurately. For example, if there is warpage in the test recording area202 and there is no warpage in the data area 203, the irradiation beamis not applied vertically in the test recording area 202, and thereforeadditional irradiation power is required compared to when the beam isapplied vertically. The recording power determined under such conditionbecomes over-power in the data area 203, thereby preventing the datafrom being correctly recorded.

<3. Operations of the Optical Disc Apparatus>

(Operations for Determining the Optimum Recording Power)

The description will be made on the operations when the optimumrecording power of the optical disc apparatus is determined.

When the optical disc 101 is loaded to the optical disc apparatus andpredetermined operations such as identification of disc type, rotationcontrol, and so on are completed, the optical head 102 moves to the testrecording area 202 for setting the optimum recording power. The optimumrecording power may be set not only when the disc is loaded. Forexample, it may also be set when the temperature of the optical discapparatus becomes out of the predetermined temperature range while thetemperature is monitored.

When the optical head 102 arrives at the test recording area 202 andbegins reproduction, the signal 111 which varies in accordance withpresence of recording mark is entered into the test recording areasearching section 109. It is noted that the signal 111 is sum ofcomponents of all the reflection signals from the optical disc 101, andsince the reflection light quantity lowers at the recording pit section,the intensity of the signal 111 lowers.

The test recording area searching section 109 detects the unused area towhich the test recording is performed. That is, the test recording areasearching section 109 judges whether the reproduction area is an unusedarea according to the signal 111. Specifically, the test recording areasearching section 109 judges whether the signal 111 achieves a levelexceeding the predetermined signal level in a predetermined range ofarea or more or in a predetermined amount of time or more. The judgmentresult is outputted to the optimum recording power determining section105 as the signal 112. When the searching section 109 cannot find theunused area on which the test recording is carried out, the testrecording area searching section jumps to a track which is apart by thepredetermined quantity and carries out the same process there.

FIG. 3 is a diagram schematically showing the test recording area 202and shows the recording status of each sector in the test recordingarea. In FIG. 3, a sector marked with “X” indicates a used or recordedsector. In the present embodiment, the light spot moves in the directionfrom the inner periphery to the outer periphery and the test recordingarea is used from the area on the outer peripheral side.

Here, using the test recording area from the outer peripheral side meansthat, for example, in case that three tracks are used in the operationfor determining one optimum power, when the second optimum recordingpower is determined after the first optimum recording power isdetermined, three tracks further inside from the three tracks which areused at the first determination are used at the second determination.

The more quickly the area that can be test-recorded is found, the morequickly the recording power can be determined, and processing can betransferred to data recording quickly. Accordingly, it is preferable tosequentially use the area from the inner peripheral side or from theouter peripheral side of the test recording area 202 as in the case ofthe present embodiment rather than randomly using the test recordingarea 202. Further, it is more suitable to continuously record so as notto leave an unused area between the used areas.

In the present embodiment, the test recording area 202 is used from apart of an area on the outer peripheral side which is closer to the dataarea 203. This is because the optimum power can be determined moreaccurately since in the outer peripheral side the disc warpageconditions and forming conditions of recording films are closer to theconditions of the data area 203 than on the inner peripheral side.

In the present embodiment, the test recording area 202 is located on theinner peripheral side of the control area 201, but it may be located onthe outer peripheral side. By setting the test recording area 202 at theposition closer to the data area 203, the warpage conditions and formingconditions of recording film of the disc in the test recording area 202are brought closer to the conditions in the data area 203, enabling moreaccurate determination of the optimum power.

That is, when test recording is carried out on random areas, even ifsufficient amount of unused areas are left, the test recording areasearching section 109 must examine the quantities of unused area eachtime, and therefore it requires much time before undertaking the testrecording. On the contrary, when test recording is done over successivearea from inner or outer side, it is enough for the searching sectiononly to find the border area between the used area and the unused area,and this enables the area for test recording to be searched in a shorttime. In addition, in the test recording with random areas, leaving theunused areas of amount insufficient for determining the optimumrecording power may reduce the frequency for finding the optimumrecording power.

FIGS. 4A to 4J are diagrams for explaining the test recording procedure.FIG. 4A shows each sector 301, 302, . . . of the test recording area202. The sector 307 marked with “X” is the used sector and sectors (notillustrated) after the sector 307 are used sectors. In addition, thesectors before sector 301 are unused and a series of test recordingshould be performed in the direction of ascending order of sectornumber. In the following, a case in which sectors before sector 306 arejudged unused and test recording begins with sector 303 will bedescribed. FIG. 4B shows signal 116 outputted from the recording section106. FIG. 4C shows the recording power value set in correspondence toeach sector of FIG. 4A. FIG. 4D shows the kind of marks recorded in eachsector.

When the area for carrying out test recording is detected by the testrecording area searching section 109, test recording is carried out withrecording power varied for each sector. A plurality of recording powerlevels are set in the recording power setting section 108 in advance.The setting of the recording power is updated sequentially based on thesignal 116 outputted from the recording section 106. In the presentembodiment, four levels of recording power are used in one testrecording operation. At the recording power setting section 108, fourpower levels of 10 mW, 11 mW, 12 mW, and 13 mW are set as initial values(see FIG. 4C).

The initial values of the recording power may be stored beforehand in amemory other than the recording power setting 108 (not illustrated).They may be set by calculations, etc. based on the recommended recordingpower of disc recorded in the control area 201 of the optical disc 101.Alternatively, if the optical disc 101 has been recorded before, theinitial value of the recording power may be set by calculations, etc.based on the recording power at that recording. In addition, the numberof recording power levels may be more than four.

The recording section 106 records the information by an optical head 102with the determined recording power while outputting the signal 117 forrecording to the predetermined sector.

FIG. 5 shows one example of the laser drive circuit 107. The laser drivecircuit 107 is equipped with a current source 501 used for reproduction,a current source 502 used for recording, and a switch 503. At thereproduction operation, the semiconductor laser 504 which is a componentof the optical head 102 emits light by the reproducing power set at thecurrent source 501. The amount of the current of the current source 502at the recording is set by the signal 115. The switch 503 turns on whena High level signal is inputted and the sum of currents from the currentsource 501 and the current source 502 flows to the semiconductor laser504. This enables the semiconductor laser 504 to emit light with therecording power set by the recording power setting section 108.

Next description will be made on the signal 117. In the presentembodiment, for test recording, 3T continuous signal and 11T continuoussignal are prepared in the recording section 106 (see FIG. 4D). The 3Tcontinuous signal is a signal for recording the 3T pit section with 3Tintervals, that is, recording a pit of 3T long at every interval of 6T,where T denotes the reference frequency (see FIG. 4G). The signal shownin FIG. 4G is modulated with the pulse width, etc. in the recordingsection 106 to be a signal shown in FIG. 4H.

Similarly, the 11T continuous signal is a signal for recording a pit 11Tlong at intervals of 22T (see FIG. 4I). The signal shown in FIG. 4I ismade into multi-pulse or adjusted with each pulse width to become asignal shown in FIG. 4J. Now, the signal shown in FIG. 4H and signal 409shown in FIG. 4J become the signal 117 to be inputed into the laserdrive circuit 107. By the foregoing configuration, continuous pits 3Tlong and the following continuous pits 11T long are formed for everysector.

Upon completion of the recording, the semiconductor laser 504 which isthe component of the optical head 102 emits light by the reproducingpower and reproduces the track which has been just recorded, and thesignal 110 which varies in accordance with a presence of recording markon the optical disc 101 is inputted into the reproducing section 103 asa reproducing signal. The reproducing signal 110 undergoes reproducingsignal process such as amplification, etc. at the reproducing section103 and the signal 111 is inputted to the reproducing signal qualitydetection section 104.

Now, one example of signal 111 is shown in FIG. 4E. FIG. 4Eschematically shows the upper limit level and the lower limit level ofeach signal at each recording power. The upper limit level depends onthe reflectance of the unused area between pits, while the lower limitlevel depends on the reflectance of the pit area. The greater the pit,the greater is occupation of the pit in the spot of the light beam andthe lower is the reflectance. As shown in FIG. 4E, regarding the 11Tsignal, both upper limit level and lower limit level do notsignificantly depend on the size of the recording power excessively, andregarding the 3T signal, as the recording power increases, both upperlimit level and lower limit level lower.

The reproducing signal quality detection section 104 detects the signalquality of signal 111 and the detection results are inputted in theoptimum recording power determining section 105 as the signal 113. Inthe present embodiment, for the reproducing signal quality, the“asymmetry values” of 3T signal and 11T signal are detected andoutputted to the optimum recording power determining section 105.

Referring now to FIG. 6, the detection method of the asymmetry valuewill be described hereinafter. FIG. 6 is an enlarged view of 3T signaland 11T signal of the signal 111. The asymmetry value A can becalculated from the following formula:A={(3T _(H)+3T _(L))/2−(11T _(H)+11T _(L))/2)}/(11T _(H)−11T _(L))where, 3T_(H) is the upper limit of the 3T signal and 3T_(L) is thelower limit of the 3T signal. 11T_(H) is the upper limit of the 11Tsignal and 11T_(L) is the lower limit of the 11T signal.

FIG. 4F plots asymmetry values at each recording power. The sign isreversed depending on whether the average level of 3T signal is above orbelow the average level of 11T signal. The optimum recording powerdetermining section 105 determines, as the optimum recording power, theaverage of recording power before and after the sign of asymmetryreverses. Here, the power before and after the sign reverses 11 mW and12 mW, respectively, and therefore the optimum recording power isdetermined as 11.5 mW which is the average of the power before and afterthe sign reverses.

In the present embodiment, in the reproducing signal quality detectionsection 104, the asymmetry value is detected, however error rate, jitterand so on may be detected. The optimum recording power determiningsection 105 can determine the recording power, as the optimum recordingpower, so that, for example, error rate or jitter becomes minimum.

Now, the error rate is the value obtained by comparing the recordedoriginal signal with the reproduced signal and finding the error rate,and under the same reproduction conditions in general, the smaller errorrate can provide more accurate recording. In addition, jitter is a timelag between the reproducing signal and the original signal, and ingeneral, the smaller jitter can provide more accurate recording.

The reproducing signal quality detection section 104 may detect themodulation factor. The modulation factor can be expressed by thefollowing equation when the recording signal is the 11T continuoussignal as shown in FIG. 12. It is noted that the recording signal may bethe signal connecting the 3T continuous signal to the 11T continuoussignal, or may be the random signal.Modulation Factor=(11T _(H)−11T _(L))/11T _(H)

The reproducing signal quality detection section 104 may detect theabove-mentioned physical quantities in combination. The section 104 maydetermine the final optimum recording power, by test recording with thepower just above and below the reference power which is obtained fromthe detection of the asymmetry value and then detecting, for example,the jitter. Combination of the above-mentioned physical quantitiesenables the more accurate determination of the optimum recording power.

(Recording to the Adjacent Area of the Test-Recorded Area afterDetermination of the Optimum Recording Power)

When the optimum recording power is determined, to the sector 302adjacent to sectors 303, 304, used for test recording, signals arerecorded with the determined optimum recording power. Signals recordedin this operation may be signals connecting 3T continuous signal to 11Tcontinuous signal same as those recorded in sectors 303, 304, 305, 306,or may be random signals.

Recording signals with the optimum recording power to the sectoradjacent to the sector to which test recording has been just performedcan provide the following advantage. That is, even when the unused areadetection section 109 has a possibility to erroneously judge thatsectors 303 and 304 are unused areas at the next test recording due to,for example, insufficient recording power to sectors 303 and 304, it ispossible to judge that sector 302 and the following sectors (that is,sectors 303, 304, . . . ) are used areas or recorded areas byreproducing the sector 302 since the sector 302 is recorded with theoptimum recording power.

It is noted that though in the present embodiment, in the sector 302,recording is carried out with the optimum recording power, the recordingmay be carried out with the power greater than the optimum recordingpower.

In addition, in the present embodiment, though the recording with theoptimum recording power is carried out only to the sector 302, therecording with the optimum recording power may be carried out to thesectors in vicinity of the sector 302 together with the sector 302. Asthe area recorded at the optimum recording power increases, it ispossible to more securely search the border between the unused area andthe used area at the next test recording. In particular, when the randomsignals is used as the recording signal for test recording, thesynchronous signal of the reproducing signal can be extracted moresecurely and the error rate can be detected more accurately.

In the present embodiment, recording with the optimum recording power iscarried out to the sector in the inner peripheral of the area where testrecording is carried out, but the recording with the optimum recordingpower may be carried out in the outer periphery of the area where testrecording is carried out after the optimum recording power isdetermined. For example, referring to FIG. 3, after determining theoptimum recording power using sectors 302 through 305, recording withthe optimum recording power may be carried out to sectors 301 and 306 onthe inner and outer peripheries of the areas of those sectors,respectively. This can prohibit misjudgement in the following case. Thatis, for example, when test recording is performed while varying thepower from the high power, the low recording power continues in thelatter half of the test recording area and therefore there is apossibility to misjudge at the next test recording that the latter halfof the test recording area is unused. This problem can be solved byrecording with the optimum recording power to the sectors on both sidesof sectors to which test recording is performed.

After recording with the optimum recording power to a sector, the testrecording area searching section 109 may confirm or verify that therecorded sector can be judged recorded or used by reproducing therecorded sector. If the sector is unable to be judged as having beenused because the sector 302 is stained, for example, by grime due tofingerprints and so on, recording with the optimum recording power iscarried out again to the sector 301. Verifying in this way the successof recording after the test recording by the test recording areasearching section 109 enables the border between the unused area and theused area to be searched more accurately at the test recording in thenext trail.

In the present embodiment, recording with the optimum recording power iscarried out to the sector 302 that is adjacent to sectors 303, 304, 305and 306 in which test recording was carried out. The recording with theoptimum recording power however may be performed to other sectors. Forexample, when six sectors of sectors 301, 302, 303, 304, 305 and 306form one block, the recording with the optimum recording power may becarried out to the sector which is at the predetermined order of eachblock, for example, at the first sector, 301. By recording theinformation with the optimum recording power to the sector with thepredetermined order of each block, it is possible to quickly judgewhether a block has been recorded only by examining the presence ofrecord in the sector of the predetermined order of the block.

Similarly, when the predetermined phase of the disc can be detected,recording with the optimum recording power may be carried out to thesector with the predetermined phase in each track. For example, for theoptical disc which has an address area at an angle of every 45°,recording with the optimum recording power may be carried out to thesector just after the address area. Alternatively, for the optical dischaving a spiral which is composed of a groove-form track connected everyone cycle with a track between grooves, recording with the optimumrecording power may be carried out to the sector just after the borderbetween the groove-form track and the track between the grooves.

As described above, recording with the optimum recording power to alocation which is detectable by features of address format or trackformat enables quick judgment on whether the adjacent predeterminedareas have been recorded by examining the presence of the record at thatposition.

In the above-mentioned description, test recording is carried out in thespot moving direction while sequentially varying the power from the lowrecording power. The recording power may be varied by other methods, andtest recording may be carried out by sequentially varying the power fromthe high recording power. Sequentially test-recording from the highrecording power could minimally suppress the effect of the judgmenterror, for example, if the test recording area searching section 109 canjudge that the sector 303 recorded with the high recording power is arecorded or used area even though it could not judge that the sector 302recorded with the optimum recording power later than the sector 303 wasrecorded.

That is, the border between the unused area and the used area can besearched more accurately by updating the recording power from the highpower side to the low power side, in case that test recording is carriedout while the light spot moves in the direction from the inner peripheryto the outer periphery, the test recording area is used from the outerperiphery side, and recording power is updated for every predeterminedrange.

Referring to FIG. 7, description will be made on the process when theoptimum recording power can not be determined even when the testrecording is carried out as described above.

FIGS. 7A through 7C show the sector status, recording power, andasymmetry value, respectively, when the first test recording has beencarried out. FIGS. 7D through 7F show the sector status, recordingpower, and asymmetry value, respectively, when the second test recordinghas been carried out. FIGS. 7A and 7D show the status of each sector ofthe test recording area 202, and the sector marked with “X” indicatesthe used sector. FIGS. 7B and 7E show the power for recording in eachsector when test recording is carried out in each sector. In FIGS. 7Cand 7F plotted are the asymmetry values when each sector with datarecorded is reproduced.

Referring to FIGS. 7B and 7C, it is found that the power is insufficientin the first test recording. The causes may include warpage in theoptical disc 101, the object lens which is the component of the lighthead 102 is stained, and so on. In such a situation, test recording iscarried out on sectors 708, 709, 710, 301 with the power higher than thefirst time as shown in FIG. 7E, and the reproducing signal qualitydetection section 104 detects the asymmetry value, and the optimumrecording power determining section 105 examines whether the recordingpower that reverses the sign of the asymmetry value is detected. Asshown in FIGS. 7E and 7F, the power before and after the reverse of thesign is 14 mW and 15 mW, respectively, and the optimum recording powerdetermining section 105 determines 14.5 mW as an optimum recordingpower, which is the average of both recording powers. If the optimumpower is unable to be determined even in the second time, the third timeand after will be carried out in the same way.

In the present embodiment, test recording is carried out to sectors 708,709, 710 and 301 with the power higher than the first time, but part ofthe power range of the first time and the second time may be overlapped.Generally, the asymmetry values of the similar level can be detected inthe sectors in which test recording is carried out with the power of thesimilar level in the first time and in the second time. It is thereforepossible to detect the asymmetry value with higher reliability withdispersions taken into account, by comparing the two results.

FIG. 8 shows the recording status of each sector of the test recordingarea 202 when the second test recording is completed. In FIG. 8, sectorsmarked with “X” mean used sectors. When the optimum recording power isdetermined, recording is carried out with the optimum recording power tothe sector 707 and sector 302. The signal recorded in such case may bethe signal with 3T continuous signal connected to 11T continuous signalsame as that recorded in sectors 708, 709, 710 and 301 or a randomsignal.

According to recording the signal to sector 707 with the optimumrecording power, it is possible to judge that sectors 707 and after(sectors 708, 709, . . . ) are used areas by reproducing sector 707 evenif the test recording area searching section 109 mistakenly judges thesesectors 708 and 709 as unused sectors due to the insufficient recordingpower of sector 708 or sector 709 because the sector 707 is recordedwith the optimum recording power.

Furthermore, by recording the signal to the sector 302 with he optimumrecording power, even if the test recording area searching section 109mistakenly judges the sector unused due to the insufficient recordingpower to sectors 303, 304, 305 and 306, it is possible to judge theareas as used areas by reproducing five consecutive sectors because thesector 302 is recorded with the optimum recording power.

For example, as shown in FIG. 9, when the first test recording iscarried out to sectors 907, 908, 909 and 910 and the second testrecording is carried out to sectors 903, 904, 905 and 906, there is apossibility of misjudgment on whether they are used by reproducing fiveconsecutive sectors. It therefore needs to reproduce the sectors ormore, and it takes additional time to detect the area in which testrecording can be carried out. In this case, by carrying out the secondtest recording to sectors 902, 903, 904, 905 and test recording tosector 901 and sector 906 with the optimum recording power, it ispossible to accurately judge the sectors used by reproducing fiveconsecutive sectors. Thus, the time taken to search the test recordingarea.

By recording signals with the recording power determined by the testrecording to the areas adjacent to the area for which test recording iscarried out as described above, it is possible to prevent the used areafrom being mistakenly judged an unused area, that is, an area enablingtest recording, and in addition it is possible to reduce the timerequired for searching the unused area.

In the foregoing description, the optimum recording power is determinedwith the recording power varied from high power to low power, while thelight spot moves in the direction from inner periphery to outerperiphery and the test recording area is used form the outer peripheralside. FIG. 10 shows another embodiment on the light spot movingdirection and the direction of using the test recording area. It isnoted that the case (A) in FIG. 10 corresponds to a mode for theembodiment described above.

FIGS. 13 through 16 schematically describe cases (A) through (D) shownin FIG. 10, respectively. In FIGS. 13 through 16, arrow marks areaffixed to sectors recorded in the latest two power learnings and thenumber is assigned in order of recording. The thickness of the arrowmark indicates the size of the recording power except No. 5 and No. 10.That is, the thicker the arrow mark, the greater is the recording power.

In case (A), the recording power level is set so that the power isvaried from high power to low power when the spot moves in the directionfrom inner periphery to outer periphery and the test recording area isused from the outer circumferential side (see FIG. 13). This enables thesector which is reproduced right after the light spot passes the borderbetween the unused area and the used area to be recorded with highpower, resulting in reduction of misjudgment as identifying the recordedsector as unrecorded sector.

In addition, as in the case (A), by taking the inner peripheral side ofthe test recording area for the area to be recorded with the optimumrecording power while the spot moves in the direction from innerperiphery to outer periphery and the test recording area is used fromthe outer peripheral side, recording with the optimum power is performedto the sector which is to be reproduced just after the light spot passesthe border between the unused area and the used area. This can reduce apossibility of misjudgment of identifying the recorded sector asunrecorded sector.

In case (B), the recording power level is set so that the power isvaried from low power to high power when the spot moves in the directionfrom inner periphery to outer periphery and the test recording area isused from the inner circumferential side (see FIG. 14). By this, thesector which is to be reproduced just after the light spot passes theborder between the unused area and the used area is recorded with highpower, and therefore a possibility of misjudgment of identifying therecorded sector as unrecorded sector can be reduced.

In addition, as in the case (B), by taking the inner peripheral side ofthe test recording area for the area to be recorded with the optimumrecording power when the spot moves in the direction from innerperiphery to outer periphery and the test recording area is used fromthe inner peripheral side, the sector which is to be reproduced justbefore the light spot passes the border between the unused area and theused area is recorded with the optimum recording power. Thus apossibility of misjudgment of identifying the recorded sector asunrecorded sector can be reduced.

In case (C), the recording power is set so that the power is varied fromlow power to high power when the spot moves in the direction from outerperiphery to inner periphery and the test recording area is used fromthe outer circumferential side (see FIG. 15). By this, the sector whichis to be reproduced just before the light spot passes the border betweenthe unused area and the used area, signals are recorded with high power,and therefore a possibility of misjudgment of identifying the recordedsector as unrecorded sector can be reduced.

In addition, as in the case (C), by taking the inner peripheral side ofthe test recording area for the area to be recorded with the optimumrecording power when the spot travels in the direction from outerperiphery to inner periphery and the test recording area is used fromthe outer peripheral side, the sector which is to be reproduced justbefore the light spot passes the border between the unused area and theused area is recorded with the optimum recording power, and therefore apossibility of misjudgment of identifying the recorded sector asunrecorded sector can be reduced.

In case (D), the recording power is set so that the power is varied fromhigh power to low power when the spot moves in the direction from outerperiphery to inner periphery and the test recording area is used fromthe inner circumferential side (see FIG. 16). By this, the sector whichis to be reproduced just after the light spot passes the border betweenthe unused area and the used area is recorded with the optimum recordingpower, and therefore a possibility of misjudgment of identifying therecorded sector as unrecorded sector can be reduced.

In addition, as in the case (D), by taking the outer peripheral side ofthe test recording area for the area to be recorded with the optimumrecording power when the spot moves in the direction from outerperiphery to inner periphery and the test recording area is used fromthe inner peripheral side, the sector which is to be reproduced justafter the light spot passes the border between the unused area and theused area is recorded with the optimum recording power, and therefore apossibility of misjudgment of identifying the recorded sector asunrecorded sector can be reduced.

In each mode shown in FIG. 10, both recording power and the position ofthe area recorded with the optimum recording power are specified inaccordance with the light spot moving direction and the direction ofusing the test recording area, but the same effects as above can beobtained by specifying either one of them.

Using FIG. 11, next description will be made on the process whenrecording is interrupted while test recording is being carried out. FIG.11 schematically shows the test recording area 202 on the optical discas well as the recording status of each sector. The sectors marked with“X” are used sectors. In the present embodiment, the spot moves in thedirection from inner periphery to outer periphery, and test recording iscarried out from the outer-peripheral side (corresponding to case (A)).

Referring now to FIG. 11, when recording is carried out in sectors 1103,1104, 1105, 1106 in the first test recording, for example, the servocomes off due to disturbance and recording is made on two sectors onlyof sectors 1103 and 1104. In such a case, before doing over testrecording again in sectors 1102, 1101, further within the sector 1103,sectors 1105 and 1106 are recorded again with the predeterminedrecording power. The recording signals to the sectors 1105 and 1106 maybe the same signals recorded in sectors 1103, 1104 or optional dummydata.

By re-recording to the area to which recording could not be carried outdue to interruption when recording was interrupted during test recordingto the predetermined area in this way, the recording area can becontinued. Thus it is possible to prevent the area from falsely beingjudged recordable.

It is noted that in the present embodiment, the re-recording to thesector in which recording was unable to be carried out due tointerruption of recording is carried out with the predeterminedrecording power, but this recording power should be, for example, themaximum power in the first recording. By using the maximum power, theunused area detection section 109 can judge more definitely that thearea is the used area.

It is also possible to perform the second test recording to innersectors 1102, 1101 when recording is interrupted and determine theoptimum recording power, and then to perform the second test recordingto sectors 1105 and 1106 in which recording could not be performed dueto interruption in the first test recording with the optimum recordingpower. This allows the unused area detection section 109 to distinguishmore definitely the unused area from the used area.

In the present embodiment, re-recording is done to sectors 1105 and 1106in which recording was unable to be carried out due to interruption ofrecording, re-recording however may be done to sectors 1103, 1104, 1105and 1106.

It is noted that, even when recording is interrupted in the middle ofthe sector and recording is done to a part of the sector, if it ispossible to judge that the area is the used area when the recordedsection of the sector is reproduced, it is not necessary to re-record inthe remaining unused area of the sector for which recording wasinterrupted.

In the present embodiment, description was made on the write-once typeoptical disc, but the invention can be applied to the re-writable typeoptical disc, in which, for example, re-recording may be performed tothe sector to which recording was unable to be carried out due tointerruption of recording. In particular, when the recording performanceof the first recording differs from that of the second recording andafter, re-recording enables recording performance of the test recordingarea between the first and second recordings to be equal.

For the re-writable optical disc, recording with the power determined bythe test recording to the area adjacent to the area to which testrecording is performed can identify the border between the used area andthe unused area in at least the first recording, and prevent testrecording to the sector to which the first test recording and the secondor later test recording has been performed, thus resulting in accuratedetermination of the optimum recording power.

Similarly, in the re-writable optical disc, it is possible to search theborder between the unused area and the used area more definitely byupdating the recording power level in test recording, for example, sothat the power is varied from high power to low power, in case that thelight spot moving direction is from inner periphery to outer peripheryand the test recording area is used from the outer peripheral side, andthe recording power is updated for each predetermined range. That is, atleast in the first recording, it is possible to clarify the borderbetween the used area and the unused area, and prevent test recording tothe sector to which the first test recording and the second or latertest recording has been performed, thus resulting in accuratedetermination of the optimum recording power.

(Application to Multi-Layer Optical Discs)

In the above-mentioned description, the method of determining theoptimum recording power for a single-layer optical disc having only onerecording layer is described. In the following, the case in which themethod is applied to the multi-layer optical disc having a plurality ofrecording layers will be described.

FIG. 17 is the diagram explaining each layer of the optical disc whichhas two layers of information recording surfaces each having the samereading light impinging surface, and areas formed on each layer. Asshown in the drawing, the optical disc 101 b includes the firstsubstrate 1701, the first recording layer 1702, adhesive resin 1703, thesecond recording layer 1704, and the second substrate 1705. The opticaldisc 101 b is provided with a clamp hole 1706. On the first recordinglayer 1702, test recording area 1707, control area 1708, and data area1709 are formed. On the second recording layer 1704, test recording area1710, control area 1711, and data area 1712 are formed.

The first substrate 1701 and the second substrate 1705 are provided toprotect the first recording layer 1702 and the second recording layer1704, respectively, and made of polycarbonate resin and so on. Thecontrol area 1708 of the first recording layer 1702 has a reproductiondedicated area in which the irradiation power information used forrecording information on the first recording layer 1702 and so on arerecorded. Similarly, the control area 1711 of the second recording layer1704 has also a reproduction dedicated area in which the irradiationpower information used for recording information on the second recordinglayer 1704 and so on are recorded.

FIG. 18 is the table showing various modes concerning the light spotmoving direction, test recording area using direction, power changingdirection and so on in the multi-layer optical disc 101 b. FIGS. 19Awith 19B through 26A with 26B are diagrams schematically explainingvarious modes (A) through (H) shown in FIG. 18, respectively. In FIGS.19A with 19B through 26A with 26B, arrow marks are affixed to sectors towhich the information has been recorded in the latest two powerlearnings, and number is assigned in order of recording. In this case,the thickness of the arrow mark indicates the size of the recordingpower except No. 5 and No. 10. That is, the thicker the arrow mark, thegreater is the recording power. The test recording may be started fromeither the first or the second recording layer.

In the modes shown in FIGS. 19A with 19B through 22A with 22B, that is,cases (A) through (D), the light spot moving direction is same betweenthe first and the second recording layers. For example, in the firstrecording layer, recording is done from inner periphery to outerperiphery, and in the second recording layer, recording is also donefrom inner periphery to outer periphery. In the modes shown in FIGS. 23Awith 23B through 26A with 26B, that is, cases (E) through (H), the lightspot moving direction is opposite between the first and the secondrecording layers. For example, in the first recording layer, recordingis done from inner periphery to outer periphery, while in the secondrecording layer, from outer periphery to inner periphery.

According to configuration as described above, in multi-layer opticaldiscs, there achieved are effects in that the light pickup does not needto return from outer periphery to inner periphery at the changeover ofthe recording layer when continuous data is recorded across tworecording layers.

According to the present invention, recording data to the area adjacentto the area in which test recording is done, with the power greater thanthe recording power determined by test recording. Thus, it is possibleto surely prevent the used area from being mistaken for the unused area,and to definitely detect the unused area, as well as to shorten thesearching time of the unused area, thereby achieving increased speed ofrecording process.

In addition; It is possible to more accurately search the border betweenthe unused area and the used area by updating the recording power fromthe high power to the low power, in case that the light spot moves inthe direction from inner periphery to outer periphery, the testrecording area is used from the outer peripheral, and test recording iscarried out while updating the recording power for each predeterminedrange.

Furthermore, when recording is interrupted while test recording in thepredetermined area, re-recording in the predetermined area including theinterrupted area allows the recording area to be continued, and thus itis possible to prevent the test-recorded area from being mistaken forthe test-recordable area (that is, unused area).

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

The present disclosure relates to subject matter contained in JapanesePatent Application No. 2001-092487, filed on Mar. 28, 2001, which areexpressly incorporated herein by reference in its entirety.

1. A method of determining a recording power used to record information to an optical disc, said method comprising: determining the recording power by test recording which records predetermined data to an area in a test recording area of the optical disc; and after the recording power is determined, continually recording predetermined data with a power equal to or more than the determined recording power to an unused area in the test recording area, the unused area being adjacent to the area in the test recording area, at which the test recording has been just carried out, to determine the recording power.
 2. The recording power determining method according to claim 1, wherein said determining the recording power comprises moving a light spot on the optical disc in a direction from an inner periphery to an outer periphery of the optical disc, and wherein the test recording area is used from the outer part to carry out the test recording, and the adjacent area is on an inside of an area where the test recording has been carried out in the test recording area.
 3. The recording power determining method according to claim 1, wherein said determining the recording power comprises moving a light spot on the optical disc in a direction from an inner periphery to an outer periphery of the optical disc, and wherein the test recording area is used from an inner part to carry out the test recording, and the adjacent area is on an outside of an area where the test recording has been carried out in the test recording area.
 4. The recording power determining method according to claim 1, wherein said determining the recording power comprises moving a light spot on the optical disc in a direction from an outer periphery to an inner periphery of the optical disc, and wherein the test recording area is used from the outer part to carry out the test recording, and the adjacent area is on an inside of an area where the test recording has been carried out in the test recording area.
 5. The recording power determining method according to claim 1, wherein said determining the recording power comprises moving a light spot on the optical disc in a direction from an outer periphery to an inner periphery of the optical disc, and wherein the test recording area is used from the inner part to carry out the test recording, and the adjacent area is on an outside of an area where the test recording has been carried out in the test recording area.
 6. The recording power determining method according to claim 1, wherein said recording predetermined data comprises recording the predetermined data with the determined recording power to areas inside and outside of a part of an area of the test recording area in which test recording has been just carried out.
 7. An apparatus for recording information to an optical disc, said apparatus comprising: a power determining section operable to determine a recording power by test recording which records predetermined data to an area in a test recording area of the optical disc; and a recording section operable to, after the recording power is determined by the power determining section, continually record predetermined data, with a power equal to or more than the determined recording power, to an unused area in the test recording area, the unused area being adjacent to the area in the test recording area, at which the test recording has been just carried out, to determine the recording power.
 8. The recording apparatus according to claim 7, wherein said power determining section is operable to move a light spot on the optical disc in the direction from an inner periphery to an outer periphery of the optical disc, and wherein the test recording area is used from the outer part to carry out the test recording, and the adjacent area is on the inside of an area where the test recording has been carried out in the test recording area.
 9. The recording apparatus according to claim 7, wherein said power determining section is operable to move a light spot on the optical disc in the direction from an inner periphery to an outer periphery of the optical disc, the test recording area is used from the inner part to carry out the test recording, and the adjacent area is on the outside of an area where the test recording has been carried out in the test recording area.
 10. The recording apparatus according to claim 7, wherein said power determining section is operable to move a light spot on the optical disc in the direction from an inner periphery to an outer periphery to the inner periphery of the optical disc, the test recording area is used from the outer part to carry out the test recording, and the adjacent area is on the inside of an area where the test recording has been carried out in the test recording area.
 11. The recording apparatus according to claim 7, wherein said power determining section is operable to move a light spot on the optical disc in the direction from an outer periphery to an inner periphery to the inner periphery of the optical disc, the test recording area is used from the inner part to carry out the test recording, and the adjacent area is on the outside of an area where the test recording has been carried out in the test recording area.
 12. The recording apparatus according to claim 7, wherein said recording section is operable to record the predetermined data with the determined recording power to areas inside and outside of a part of an area of the test recording area in which test recording has been just carried out. 